The present invention relates generally to a support structure that can be used to support shelving or other elements for carrying or supporting any desired item. More particularly, the present invention relates to a support assembly for use in, for example, a knock-down shelving system to adjustably support shelves.
Current knock-down shelving systems include a plurality of support posts for supporting one or more shelves at corner support assemblies thereof. These shelving systems have a sleeve or wedge member and an encircling collar both adapted to be secured to a generally cylindrical support post having a circular cross-section. The sleeve has an inner surface that is configured to embrace the support post and has an outer surface that is wedge shaped usually taking the form of a frusto-conical shape with a narrower diameter at the top and a larger diameter at the bottom. The collar has an outer surface that is secured to a shelf. The collar has an internal wedge surface formed to mate with the frusto-conical wedge surface of the sleeve but either inclined in the opposing direction or having a smaller upper opening which does not allow passage of the sleeve on the post. Thus, when the sleeve embraces the post and the collar embraces the sleeve, axial loading of the collar in one direction causes the collar's inward facing wedge surface to mate with the outward facing wedge surface on the sleeve, thereby urging the sleeve toward the post. Since the collar is restrained from radial expansion and has a fixed diameter, and since relative movement of the inclined surfaces of the sleeve and the collar want to increase in diameter as they move relative to one another in axially opposing directions, the non-expandable outer collar forces the sleeve inward and clamps the sleeve against the post and wedges the collar and sleeve into place on the post.
Such shelving systems are disclosed in U.S. Pat. Nos. 3,424,111 and 3,523,508, which use a plurality of cylindrical support posts each formed with a series of equally spaced, annular grooves on its outer surface. A basic shelving system includes four such posts to support one or more formed-wire shelves, with each shelf having a frusto-conically-shaped collar at each corner for receiving a support post. A two-piece interlocking sleeve fits around the support post. The sleeve has a circumferential rib on its interior surface for engaging one of the grooves on the support post and has a frusto-conically-shaped outer surface, which is widest at the bottom, designed to complement the shape of the shelf collars. The support posts fitted with sleeves are received in the collars of each shelf to assemble the shelving system. When assembled, the weight of the shelf and any items placed on the shelf pushes downward on the collar and sleeve, creating a radially-inwardly directed wedging force between the collars and sleeves, which brings the sleeves into tight contact with the posts.
Similar wedging concepts are used in U.S. Pat. Nos. 4,811,670; 4,946,350; 5,271,337; 5,279,231 and 6,113,042. Some of these devices use over-center cams to ensure the collars are locked in place.
Further, the above described collars have a fixed diameter and thus pass along the length of the post until they reach the sleeve with which they wedge against the post. That requires assembling the shelving from the bottom up or the top down since the collars cannot be positioned between two previously installed shelves. Further, a shelf cannot be inserted between pre-installed shelves since the collars cannot slide over previously installed sleeves or collars. Because the collars in these prior art connectors were tubular they had to be slid axially over one end of the post in order to mate with the sleeve and wedge the parts in place. To address this difficulty collars which encircles less than a full 360 degrees were developed, with some collars having open vertical slots like U.S. Pat. Nos. 6,302,284 and 6,257,426, and other collars mating with sleeves or other parts along generally vertical axes, as described in U.S. Pat. Nos. 6,068,143 and 4,656,952. But the open slotted collars provide a weak connection because sufficient weight on the shelf and collar will spread the unconnected parts of the collar apart, releasing he support. The collars mating with shaped sleeves required more expensive and stronger sleeves. The collars using vertical joints require precise alignment of the vertical joints making them difficult to align and assemble.
Despite the long use of these above-described shelving systems, a need exists for an improved connector and shelving system, especially one easier to assemble and more flexible in its assembly. There is thus a need for an improved shelving connector that may be installed without having to slide the connector along the entire length of the post to the desired shelving position and that may be easily installed.